I'd rather someone told me if hey knew me from BB. Mainly because I kind of feel like I'm eavesdropping if I don't tell someone. I would have no issue itch someone saying 'hey! I know you from BB'. I would have an issue with someone reading my posts/thoughts and pretending they didn't. This is a public place, as is a blog so you almost need to expect that people will recognize you, particularly if you post pics and personal details.